Gravity, Conservation of Momenta and Cosmic Acceleration,
If you have two initially static masses, small A and big B, between which there is a gravitational attraction, causing them then to move towards each other, you might say that from A’s reference frame it is all B accelerating towards A and from B’s reference frame it is A accelerating towards B.
However, in either case description, the motion is not agreeing with a conservation of momentum between the two (to every action there is an equal and opposite reaction).
In reality the spatial context is defined such that there is an overall conservation of momentum (in all gravitational motion) so A and B are moving towards each other (at a rate where their respective momenta are equal)
Now consider the scenario where you have a small collective mass X, surrounded in all directions by a much larger (infinite) collective mass Y, again initially static.
Gravity may cause the collective mass Y to move toward X, i.e. to contract – and that would agree with an overall conservation of momentum - however we are also saying that only the masses of Y are moving while X’s remain static.
Should we not also be saying that if the masses of Y are moving inwards toward X then the masses of X must also be defined as moving outwards toward Y (such that the inward momentum of Y is equal to the outward momentum of X)?
The simple problem with this is that whilst all the masses of Y each have a definable direction to go in (towards X), all the masses of X each have no definable direction to go in that is towards Y.
However, referring back to the A and B scenario, we know it is the spatial context that is defined to make the motion of A and B equal and opposite.
In the case of X and Y then, although/because the masses of X have no definable direction to go in, the spatial context of X can/would expand in order to effect a motion that is equal and opposite to Y’s motion. None of the masses of X are then defined as going in a direction, but they are nevertheless moving apart.
Hence we have an explanation for the accelerating expansion of our cosmos (X) if it is surrounded by a greater infinite universe (of infinite other cosmoses) (Y)
